INTRODUCTION
The basic building blocks of electronic equipment are individual circuits made up of transistors, resistors, capacitors, and sometimes transformers, inductors or other components. It used to be that circuits were made up of individual discrete components that were wired together on a printed circuit board. But today, most electronic circuits are in integrated circuit (IC) form or more likely multiple circuits are already combined on a single silicon chip to create a larger circuit, sub-system or system on a chip (SoC).
While most circuits are ICs there are still some cases where discrete components are necessary or desirable. The most common examples are high voltage or high power circuits that would burn up a tiny silicon chip. Discrete components have not gone away entirely and you will find some of them external to an IC such as larger capacitors or inductors that just cannot be easily integrated on- to a chip or transistors that can handle higher voltage or power. As mentioned before, we are not going to talk about the make-up or operation of individual circuits, Instead, this book treats circuits as just building blocks with an input and an output that process the input in some way to create a new, different output.